HR: 0800h
AN: A51A-0011    [Abstracts]
TI: Drizzle as Additional Diabatic Forcing Within the STBL
AU: * Savic-Jovcic, V
EM: verica@atmos.ucla.edu
AF: UCLA Atmos & Ocean Sci, BOX 951565, Los Angeles, CA 90095-1565 United States
AU: Stevens, B
EM: bsteves@atmos.ucla.edu
AF: UCLA Atmos & Ocean Sci, BOX 951565, Los Angeles, CA 90095-1565 United States
AB: Recent observations of coincidence of pockets of open cells (POCs) and drizzling episodes within the stratocumulus-topped boundary layer (STBL) over the Eastern Pacific motivated this modeling study. We are particularly interested in the dynamical framework of the phenomenon and its dependence on the diabatic aspect of precipitation. Therefore, we employed the UCLA LES with two simple microphysical schemes, one based on Seifert and Beheng (2001) and another on Khairoutdinov and Kogan (2000). Both parameterizations are double-moment schemes with prognostic equations for mass and number concentrations of drizzle drops, while the number concentration of the cloud droplets is preserved throughout the simulation wherever the cloud is present. By varying the domain size of the simulation, we explore the scales of interaction of turbulence within the STBL and the diabatic aspect of drizzle. We also explore how simulations of drizzling stratocumulus degrade as the resolution coarsens. Finally, we examine how different representations of precipitation alter the energy distribution within the STBL and its impact on the evolution of turbulent eddies. References Khairoutdinov, M. and Y. Kogan, 2000: A new cloud physics parameterization in a large-eddy simulation model of marine stratocumulus. Mon. Wea. Rev., 128, 229- 243. Seifert, A. and K. Beheng, 2001: A double-moment parameterization for simulating autoconversion, accretion and selfcollection. Atmos. Res., 59-60, 265-281.
DE: 3307 Boundary layer processes
DE: 3314 Convective processes
DE: 3354 Precipitation (1854)
DE: 3379 Turbulence (4490)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005